EATC Stuck on Dash Vents

[brianzpatton]

I have a strange problem. My EATC is stuck on blowing through the dash vents only. It doesn't default to the defroster mode like a vacuum leak. I have replaced the O-rings in the EATC according to a post here in these forums. I can see the solenoids in the dash behind the EATC moving when I switch between AC/Floor/Vent/Defrost modes but it never switches from the dash vents. The blower speeds operate properly. The temperature operates properly. Any ideas???

[CBT]

Hi, sailor! Welcome aboard! :wave:

[fastblackmerc]

Go back and check the red electrical connector inside the EATC... the one you took off to access the solenoids. Make sure it's on all the pins.

[brianzpatton]

The dash vent only blowing started before I took the EATC apart and changed the O-rings. I did go back and check the wiring connectors. Both the red and white connectors are properly seated. I do not receive any error codes when I run the diagnostic on the EATC unit. Is there some type of flap that directs the airflow that the spherical metal actuators connect to inside the dash? Thanks for the help and hospitality.

[fastblackmerc]

The dash vent only blowing started before I took the EATC apart and changed the O-rings. I did go back and check the wiring connectors. Both the red and white connectors are properly seated. I do not receive any error codes when I run the diagnostic on the EATC unit. Is there some type of flap that directs the airflow that the spherical metal actuators connect to inside the dash? Thanks for the help and hospitality.

Maybe one of the solenoids is not reassembled correctly.

The solenoids direct vacuum to the various vacuum motors which in turn open or close doors to direct airflow, heat and / or cooling to the vents dependent on the EATC settings.

[brianzpatton]

I completely replaced the O-rings again and still having the same problem. I noticed upon closer inspection that the airflow is not shut off to the dash vents on any mode selected. When I select DEFROST or FLOOR, airflow comes from the selected mode as well as the dash vents. When I select VENT, MAX AC, or NORM AC, airflow comes from the dash vents only. The temperature operates and mixes properly. I see the 2 metallic spherical units behind the EATC moving their armatures in and out when I select the different modes. Is there a door that the armature attaches to that could be jammed or obstructed? I can manually close all the dash vents in order to obtain a sufficient defrost airflow, but that really sucks. :) Any other help would be greatly appreciated. If I get this thing fixed, O-rings for everyone!!!!!

[fastblackmerc]

I completely replaced the O-rings again and still having the same problem. I noticed upon closer inspection that the airflow is not shut off to the dash vents on any mode selected. When I select DEFROST or FLOOR, airflow comes from the selected mode as well as the dash vents. When I select VENT, MAX AC, or NORM AC, airflow comes from the dash vents only. The temperature operates and mixes properly. I see the 2 metallic spherical units behind the EATC moving their armatures in and out when I select the different modes. Is there a door that the armature attaches to that could be jammed or obstructed? I can manually close all the dash vents in order to obtain a sufficient defrost airflow, but that really sucks. :) Any other help would be greatly appreciated. If I get this thing fixed, O-rings for everyone!!!!!

Are you sure you connected the electrical connector inside the EATC the right way? The 2 prongs on the red connector go towards the outside of the EATC (looking at the EATC with the controls facing you).

With the inside of the EATC with the controls facing you the white connector is on the middle connector and the red connector is closer to the top.

I'd also check all the vacuum lines under the dash. Look for broken, pinched or disconnected lines.

[brianzpatton]

I have checked the electrical connections and they are good. The hoses hold suction from the rubber connector to the EATC. Only the middle connector holds suction on the EATC itself. Is that a problem? I am gonna look for a used one in a junkyard just to test if it is the EATC or the lines in the dash. Trying to figure out why the vents have airflow no matter what the EATC setting. I thought that the default was to the defroster if vacuum was lost.